1. Field of the Invention
The present invention relates to a display system, and in particular, to a multi-resolution display system.
2. Description of the Related Art
Conventional display such as Liquid Crystal Display (LCD), Organic Light Emitting Diode (OLED), Electronic Paper Display (EPD) display has only one native physical resolution, which is determined by the number of full color RGB pixels physically built into the display. A display with a native resolution of 640×RGB×480 means that there are 640×480=307,200 full color RGB pixels. If the input signal to this display has a resolution differing from the native resolution 640×RGB×480 of the said display, a scaler needs to rescale the input signal to match exactly the given native resolution of the said display.
Nowadays, consumers tend to opt for an universal display device, specially a mobile device, which could fulfil different applications such as electronic book (eBook), Ultra Mobile Personal Computer (UMPC), Portable Media Player (PMP), Geographic Positioning System (GPS) . . . with power efficiency function and indoor/outdoor readability. Since power saving is very critical for a mobile device, especially for a LCD display, such an universal mobile device tends to be transmissive (backlight illuminates the display) and reflective (ambient light reflection illuminates the display), and the general terminology is a transflective display. On the other hand, by using a multi-primary pixel display such as a quadpixel of Red, Green, Blue and White (RGBW), the brightness increases considerably because the white color dot is usually a transparent coating on the color filter of a LCD display and it lets white backlight goes through stronger than through other primary colors R, G and B. For LCD reflective display mode and Electronic Paper Display, where usually there is only one reflective mode, the benefit to add a white dot on a RGB pixel is also important because the white color reflects more light than R, G and B.
US Patent Publication No. 2005/0068287 discloses a multi-resolution driver device. Depending on the input image data resolutions, which are lower or equal to the native physical resolution of a given display, the physical pixels may be driven individually in sequence, or two or more physical pixels may be grouped as a logical pixel (i.e., driven simultaneously with same data) and adjacent logical pixels are driven in sequence using shift registers and switches in the driver device. The motive of this driven method is mainly to lower the transmission data rate of the system device to the display device with lower input image data resolution, thus achieving the power saving on the system side for a certain application mode. The downside of this method is that it uses a high-resolution display as the base to accommodate lower input image data resolution by grouping and driving two or more physical pixels simultaneously, thus lower the display performance while maintaining the high power and high cost of the high resolution display.
Usually for such a display system, the usage ratio of the low input image data resolution mode, such as text and menu mode in a mobile device, is much higher than the usage of the native high-resolution display mode, such as image/video mode, then the adoption of a high-resolution, backlight power hungry and high cost mobile display module does not justify the power saving in the system module side.
On the other side, this multi-resolution display system requires that the operating system (OS) in the system module supports the dynamic resolution mode to change different image data resolutions on the fly but nowadays system OS such as Window Mobile from Microsoft does not support dynamic resolution mode.
Therefore, it is necessary to provide a multi-resolution display system to solve the above-mentioned problems.